Overhead athletes often suffer from elbow injuries due to repetitive throwing movements. In particular, in the baseball pitching motion, a high shear torque generated in the late corking and early acceleration stage causes tensile loads on the medial elbow and shear force on the posterior of the elbow. These repetitive movements can lead to valgus extension overload syndrome. The valgus extension overload syndrome mainly occurs in overhead athletes, and is characterized by limited elbow flexion and pain at the end of extension. It is necessary to differentiate from the stress fracture or the avulsion fracture of the olecranon which complain of posterior elbow pain through computed tomography. The treatment is primarily rehabilitation that restricts the elbow motion. If refractory or mechanical symptoms persist, arthroscopic surgery may be an effective treatment modality for the removal of the osteophytes. In the surgical field, it is desirable to reconstruct the medial collateral ligament when it is confirmed that the ligament is ruptured. Patients who underwent arthroscopic removal of olecranon osteophytes had immediate active elbow exercises and for 3 months were prohibited from pitching exercises. During this period, they were rehabilitated with the focus on strengthening muscles around the scapula, rotator cuff and shoulder. After 3 months, the pitching exercise is gradually started. Six months after the operation, the elbow strength should be restored to the level at which the game starts. Patients who underwent a combined ulnar collateral ligament reconstruction, half pitching are allowed at 6 months.